FIG. 1 illustrates a network structure of a Universal Mobile Telecommunication System (UMTS) according to a conventional art. More specifically, the UMTS comprises a User Equipment (UE), a UMTS Terrestrial Radio Access System (UTRAN), and a Core Network (CN). The UTRAN further comprises more than one Radio Network Sub-systems (RNS) and each RNS comprises a Radio Network Controller (RNC) and at least one base station (Node B) which is managed by the RNC. Moreover, each Node B comprises at least one cell. Hereafter, the UE can be alternatively referred to as a mobile terminal, a mobile station, a terminal, to name a few.
FIG. 2 illustrates a structure of a Radio Interface Protocol between the UE and the UTRAN based on a 3rd Generation Partnership Project (3GPP) wireless access network standard. As illustrated in FIG. 2, the Radio Interface Protocol comprises, horizontally from bottom up, a physical layer, a data link layer, and network layer. In addition, the Radio Interface Protocol comprises, vertically from left to right, a control plane for transmitting control signals and a user plane for transmitting data. Furthermore, the protocol layers can be classified into Layer 1 (L1), Layer 2 (L2), and Layer (3) which is based on bottom three layers of an Open System Interconnection (OSI).
L1 or the physical layer uses a physical channel to provide Information Transfer Service to the upper layer. Structurally, the physical layer is connected to a Medium Access Control (MAC) layer via a transport channel through which data is transferred. At the same time, data transmission between the transmission end and the receiving end of the physical layer take places through the physical channel.
The MAC layer of L2 uses a logical channel to transfer information to higher layer or a Radio Link Control (RLC) layer. The RLC layer can support reliable data transmission and can perform segmentation and/or concatenation on a Service Data Unit (SDU) transferred from higher layer.
A Radio Resource Control (RRC) of L3 is operational only in the control plane. The RRC controls configuration, re-configuration, and release of a Radio Bearer (RB) in relation to the logical channel, transmission channel, and physical channel. Here, the RB represents service(s) provided from L2 between the UE and the UTRAN for data transmission. A configuration of the RB generally signifies specific characteristic of the protocol layer(s) and channel(s) necessary for providing a specified service and configuration of parameters and operational schemes.
A detailed description of a Multimedia Broadcast/Multicast Service (MBMS) will be explained. The MBMS uses a MBMS bearer service to provide streaming or background services to a plurality of UEs. The MBMS service comprises at least one session, and the MBMS data is transmitted only during the operation of the session through the bearer service.
FIG. 3 illustrates a structural diagram of a MBMS service from the perspective of the UE according to the conventional art. As illustrated in FIG. 3, the UTRAN uses the RB to provide the MBMS bearer service to the UE. Here, the RBs can be represented with two types, namely, a point-to-point RB and a point-to-multipoint RB. Here, the point-to-point RB is a bi-directional RB and is comprised of a logical channel (i.e., Dedicated Traffic Channel (DTCH)), a transmission channel (i.e., Dedicated Channel (DCH)), and a physical channel (i.e., Dedicated Physical Channel (DPCH) or Secondary Common Control Physical Channel (SCCPCH)). Moreover, the point-to-multipoint RB is a uni-directional downlink RB, and as illustrated in FIG. 3, is comprised of a logical channel (i.e., MBMS traffic Channel (MTCH)), a transmission channel (i.e., Forward Access Channel (FACH), and a physical channel (i.e., SCCPCH). More specifically, the logical channel MTCH is configured during each MBMS service provided to the cell and is used provide user plane data to a plurality of UEs.
Furthermore, a logical channel MBMS Control Channel (MCCH) is a point-to-multipoint downlink channel used to transmit MBMS related control information. The logical channel MCCH is mapped to a Forward Access Channel (FACH), and the FACH is mapped to the SCCPCH. In addition, one MCCH exists per each cell.
The conventional art related to the discussion above has following shortcomings. In the conventional art, in order for the UTRAN to transmit a large amount of information on the MCCH during a single modification period, the UTRAN increased a transmission rate of the MCCH or simple extended the transmission period. However, if the MCCH transmission rate is increased, Node B consumes more power, and at the same time, modification of the MCCH information can be delayed.